This invention relates to devices for detecting and removing water which may contaminate fuel in storage tanks.
The presence of water in gasoline and other fuels can, if it is drawn into the fuel supply system, cause serious problems. For example in internal combustion engines, especially for aircraft, water can cause serious engine malfunction, and even stall the engine. For this reason, many fuel tanks, and all aircraft fuel tanks, are provided with sump drains for draining water from the tanks. The water collects at the bottom, because it is immiscible and its specific gravity is greater than that of gasoline. The technique is usually to open a petcock and drain some liquid from the tank. If only gasoline flows out (and this can be observed by its color), the valve is closed. If only water is withdrawn, flow is continued until gasoline leaves the valve. Then the valve is closed. In both situations, gasoline is wasted, and usually drips on the ground, and often onto the mechanic or pilot. This is wasteful, messy, and hazardous. It would be advantageous to open the drain only if there were water present, and sometimes only if excessive water were present. Then the valve would not be opened unnecessarily. Because of the volatility of the gasoline, it is very desirable that a voltage not be applied to a test circuit to determine the presence or absence of water. Instead, the device should be self-generating, and passive relative to the gasoline.
A device for detection of water in a fuel tank is described and disclosed in U.S. Pat. No. 4,304,132. However, a disadvantage of the device disclosed in this patent is the necessity of connection and disconnection of a meter to test each tank. The disadvantage of this system is that some aircraft will have numerous fuel tanks making testing of each tank time consuming and tedious. Multiplying this by the number of aircraft which need daily checks, obviously could be a time consuming process. It would be advantageous if excess water in a tank could be detected simply by a quick visual inspection alone.